In recent years, the oil and gas industry has found significant oil and gas reserves in deepwater offshore locations. The subsea technology of today has limitations when it is deployed at these water depths. At these water depths the compactness of the equipment used is critical during installation and maintenance thereof. A compact system will ease the installation process and lower the installation costs since smaller installation vessels can be deployed. The maximum weight for a single lift is decreasing with increasing water depth and some equipment that could be used at shallower water depths will be impossible to install due to their weight and size (typically large gravity separators).
Numerous solutions to deal with the weight and size limitations of gravity separators have been suggested based on other and more compact technologies than gravity separation. Some of these technologies come to short when it comes to reliability and failure rates. For instance, cyclone technology alone may fulfill the compactness requirements, but will have difficulties to meet the important reliability criteria as to dealing with e.g. variations in process conditions.
Thus, the use of gravitational settling by means of gravity separators, in combination with or in addition to supplementing techniques such as hydro cyclones, electrostatic coalescers, etc may be regarded as the most efficient and reliable way in order to achieve sufficient separation of oil from water, gas and possible solid particles, such as sand, at large water depths as well as on the surface or on land.